In glassware forming machines of the I.S. type there are two common modes of operation blow and blow and press and blow. These modes are distinguished by the method of formation of a parison in a parison mould, but both methods utilize a plunger which is forced into molten glass in the parison mould in the formation of the parison.
Plunger assemblies for parison formation are normally operated by a pneumatic piston and cylinder device, and the plunger assembly is attached to an upper end portion of a piston rod of the piston and cylinder device by use of an adapter comprising a sleeve having a wall portion with an internal threaded bore adapted to screw on to the upper end portion of the piston rod. It is essential that the adapter does not work loose while the machine is operating, because if it does so the height of the plunger in the machine may change, giving rise to defective ware. It is customary therefore for an operator to tighten the adapter onto the piston rod as much as possible. This gives rise to great problems when for example to change the plunger assembly, it is desired to remove the adapter during an operating run of the machine, partly because of the difficulty in obtaining a proper purchase on the adapter and partly because the parts of the machine are hot, and differential expansion can tighten the adapter even further.
It is an object of the present invention to provide an improved adapter.